Rapid Correction of Hyponatremia in the Syndrome of Inappropriate Secretion of Antidiuretic Hormone

In the syndrome of inappropriate secretion of antidiuretic hormone, life-threatening cerebral dysfunction may necessitate rapid elevation of the serum sodium concentration. Treatment with fluid restriction may be too slow, and infusions of hypertonic saline are excreted because these patients already have volume expansion. Severe hyponatremia in five patients was corrected by inducing a diuresis with furosemide and by replacing the urinary electrolyte losses. The mean plasma sodium concentration increased in these patients from 120 ± 1 to 133 ± 2 meq/litre (P < 0.001) in 6 to 8 hours. Before treatment one of these patients was semicomatose and had grand mal seizures, symptoms that subsided as the serum sodium concentration was rapidly elevated. Although the furosemide diuresis consistently diminished urine to plasma osmolality ratios, a negative water balance may be achieved at all levels of urinary osmolality, provided the urinary electrolyte losses are replaced in a more concentrated solution.